A LIMIT-POINT CRITERION FOR REAL POLYNOMIALS IN SYMMETRIC QUASI-DIFFERENTIAL EXPRESSIONS OF ARBITRARY ORDER

Abstract

A limit-point criterion for symmetric quasi-differential expressions of arbitrary order with matrix-valued coefficients is given. This criterion is also sufficient for real polynomials in such expressions to be in the limit-point case. In the scalar case it includes a number of known results most of which were proved by asymptotic methods.